Up to now, data recording and/or reproducing apparatus, such as an IC recorder, employing a semiconductor memory as a recording medium, an MP3 (MPEG1 Audio Layer 3) recorder, an MO drive employing a magneto-optical disc, used in a personal computer, as a recording medium, or a CD drive employing a recording type optical disc as a recording medium, have been used. The recording medium used for this recording and/or reproducing apparatus may be mounted to or dismounted from the apparatus. The recording medium, that may be mounted to or dismounted from the recording and/or reproducing apparatus, need to be mounted to or dismounted from plural apparatus at least of the same sort. A large variety of contents data, such as music or motion pictures, are recorded on the recording mediums that may be mounted to or dismounted from the recording and/or reproducing apparatus. The recording medium, having recorded thereon a variety of contents data, proves to be an object of commercial transactions, by itself, and is circulated in the market.
With enhanced volume of transactions of the recording mediums, having recorded contents data thereon, illicit use or plagiarism of the contents data is also increasing.
For positively prohibiting the illicit use or plagiarism of the contents data under this situation, it is necessary that, even though the recording and/or reproducing apparatus are designed to allow the use of the same sort of the recording medium as that having recorded the contents data, only specified recording and/or reproducing apparatus, allowed for using the recording medium having recorded the contents data, are able to record and/or reproduce the contents data. That is, the recording medium, having the contents data recorded thereon, needs to be provided with the authenticating function of allowing only a specified recording and/or reproducing apparatus to record and/or reproduce the contents data recorded on the recording medium or to transmit the contents data.
As typical of the reciprocal authenticating system comprising a recording medium provided with this sort of the authenticating function and a recording and/or reproducing apparatus employing this sort of the recording medium, there is a system disclosed in Japanese Laying-Open Patent Publication H-11-265318. The reciprocal authenticating system, disclosed in this patent publication, uses such a method in which passwords are exchanged between the recording and/or reproducing apparatus and the recording medium, by way of performing reciprocal authentication, in order to check for accessibility of the apparatus to the recording medium. With this method, only a sole recording and/or reproducing apparatus is entitled to record and/or reproduce plural recording mediums, while it is not possible for plural authorized data recording and/or reproducing apparatus to record and/or reproduce plural recording mediums. For overcoming this deficiency, known authenticating functions use a method in which, for checking into accessibility of the plural recording and/or reproducing apparatus to the recording medium, the reference information is also recorded at the time of data recording on the recording medium for use for checking into accessibility to the recording medium. This reference information is the information set in advance for the recording and/or reproducing apparatus by the producer of the apparatus. This reference information includes, for example, the authentication information for coping with e.g. plural recording and/or reproducing apparatus.
This reference information is susceptible to adulteration. With this in mind, the known authentication system signs the reference information, stored in the recording medium, with a private key of the formulator of the reference information. On the other hand, the party exploiting the reference information verifies the signature with a public key to confirm the validity (authenticity) of the reference information.
For confirming the signature by the public key, a public key, demonstrated by the authentication authorities, as a third party organization, is routinely employed. On the equipment exploiting the reference information, such as the recording and/or reproducing apparatus, such a function must be mounted by means of which it is possible to confirm the authenticity of the signature. The result is that, with the conventional method, signature verification by the public key tends to be expensive.